Re-write equation without multiplication

Oct 2009
Hi guys,

I have an equation y = a*b + c*d

The variables are just real numbers. How can I get this equality to hold without multiplying anything together? I have tried taking the log of each side but that doesn't work.

Anyone have any thoughts?


MHF Hall of Honor
May 2006
Lexington, MA (USA)
Hllo, sfspitfire23!

Are you sure of the wording of the problem?
I don't think it can be done.

Rewrite without multiplication: .\(\displaystyle y \:= \:ab + cd\)
The variables are real numbers.

It might help if we knew what course this problem came from.

If the variables were natural numbers, the task can be completed.

. . \(\displaystyle \text{For example: }\:a\cdot b \;=\;\underbrace{b + b + b + \cdots + b}_{a\text{ terms}} \)

But with real numbers . . . I see no way to rewrite\(\displaystyle \pi\sqrt{3}\)
Oct 2009
Just a linear algebra course. My teacher wants to know whether it can be done. I don't think it can.